1. strtoupper echo "justcode.ikeepstudying" | tr '[:lower:]' '[:upper:]' #JUSTCODE.IKEEPSTUDYING   其他方法： echo 'justcode.ikeepstudying.com' | awk '{print toupper($0)}' #JUSTCODE.IKEEPSTUDYING echo "justcode.ikeepstudying.com" | tr /a-z/ /A-Z/ #JUSTCODE.IKEEPSTUDYING.COM $ tr [a-z] [A-Z] < convert_to_uppercase.txt #JUSTCODE… Read More